Chronic obstructive pulmonary disease is persistent obstruction of the airways occurring with emphysema, chronic bronchitis, or both disorders.
In the United States, about 12 million people suffer from chronic obstructive pulmonary disease (COPD). It is second only to heart diseases as a cause of disability that forces people to stop working. It is the fourth most common cause of death, accounting for more than 120,000 deaths per year in the United States. The number of deaths from COPD has increased more than 60% over the last 20 years, and more than 95% of all COPD-related deaths occur in people older than age 55. COPD affects men more often than women, but men ad women die as a result of COPD at about equal rates. COPD is more often fatal in whites than in nonwhites and in blue-collar workers than in white-collar workers.
COPD leads to chronic airflow obstruction, which is defined as a persistent disease in the rate of airflow from the lungs when the person breaths out (exhales). This airflow obstruction is partially reversible in most people, either spontaneously or with treatment. COPD includes the diagnoses of chronic obstructive bronchitis and emphysema. Many people have both disorders. Chronic bronchitis is defined as cough that produces sputum repeatedly during two successive years. When chronic bronchitis involves airflow obstruction, it qualifies as chronic obstructive bronchitis. Emphysema is defined as widespread and irreversible destruction of the alveolar walls (the cells that support the air-sacs, or alveoli, that make up the lungs) and enlargement of many of the alveoli.
The small airways (bronchioles) of the lungs contain smooth muscles and are normally held open by their attachments to alveolar walls. In emphysema, the destruction of alveolar wall attachments results in collapse of the bronchioles, causing permanent airflow obstruction. In chronic bronchitis, the glands lining the larger airways (bronchi) of the lungs enlarge and increase their secretion of mucus. Inflammation of the bronchioles develops and cause smooth muscle in contract (spasm), further obstructing airflow. Inflammation also causes airflow to be blocked by secretions. Asthma is also characterized by airflow obstruction. However, in contrast with the airflow obstruction of COPD, the airflow obstruction of asthma is completely reversible in most people, either spontaneously or with treatment.
The airflow obstruction of COPD causes air to become trapped in the lungs after a full exhalation, increasing the effort required to breathe. Also in COPD, the number of capillaries in the walls of the alveoli decreases. These abnormalities impair the exchange of oxygen and carbon dioxide between the alveoli and the blood. In the earlier age of COPD, oxygen levels in the blood may be decreased, but carbon dioxide levels remain normal. In the later stages, carbon dioxide levels increase and oxygen levels fall.
The decrease in oxygen levels in the blood stimulates the bone marrow to send more red blood cells into the bloodstream, a condition known as secondary polycythemia. The decrease in oxygen levels in the blood also increases the pressure in the artery through which blood flows from the heart to the lungs (Pulmonary artery). As a result of the increase pressure, pulmonary hypertension and cor pulmonale can occur. The people with COPD also have an increased risk of developing heart rhythm abnormalities (arrhythmias) For smokers, the risk of developing lung cancer is higher than it would be on the basis of cigarette smoking alone.
Causes Of Chronic Obstructive Pulmonary Disease
Cigarette smoking is the most important cause of COPD, although only about 15% of smokers develop the disease. Pipe and cigar smokers develop COPD more often than nonsmokers but not as often as cigarette smokers. With aging, susceptible cigarette smokers lose lung function more rapidly than nonsmokers. Lung function improves only a little if people stop smoking. However, the rate of decline of lung function returns to that of nonsmokers when people stop smoking, thus delaying development and progression of symptoms.
COPD tends to occur more often in some families, so there may be an inherited tendency. Working in an environment polluted by chemical fumes or dust may increase the risk of COPD. Exposing to air pollution and to smoke from nearby cigarette smokers (secondhand or passive smoke exposure) may cause COPD (and also worsens the disease).
A rate cause of COPD is a hereditary condition in which the body produces a markedly decreased amount of the protein alpha-antitypsin. The main role of this protein is to prevent neutrophil elastase (an enzymein certain white blood cells) from damaging the alveoli. Consequently, emphysema develops by early middle age in people with severe alpha-antitrypsin deficiency (also called alpha-antiprotease inhibitor deficiency), especially in those who also smoke
Treatment Of Chronic Obstructive Pulmonary Disease
The most important treatment for COPD is to stop smoking. Stop smoking when the airflow obstruction is mild or moderate often lessens cough, reduces the amount of sputum, and slows the development of shortness of breath. Stopping smoking at any point in the disease process provides some benefit. Trying several strategies at once is most likely to be effective. Among these strategies are committing to a specific date for quitting, using behavioral modification techniques (for example, making cigarette difficult to obtain or rewarding oneself for abstaining for increasingly long periods of time), group counseling and support sessions, nicotine replacement (for example, by chewing nicotine gum, wearing a nicotine skin patch, or using a nicotine inhaler, nicotine lozenge, or nicotine nasal spray). The lungs varenicline and bupropion may also help decrease tobacco craving. However, even with the most effective methods, less than half of people have quit smoking after one year.
People should also try to avoid exposure to other airborne irritants, including secondhand smoke and air pollution.
Contracting influenza or developing pneumonia may worsen COPD markedly. Therefore, all people with COPD should receive an influenza vaccination every year and a pneumococcal vaccination every year 5 or 6years.